F. G. Badía

Optimal inspection and preventive maintenance of units with revealed and unrevealed failures

Abstract The maintenance of a single unit system that alternates operating and idle periods is studied. In the former case the failures are detected as soon as they occur and only by special testing or inspection in the latter. This paper aims at minimizing the cost per unit of time for an infinite time span by selection of a unique interval, for both inspection and maintenance. A special feature of this model is the possibility of a less than perfect testing as the inspections may fail and give a wrong result. It is further assumed that both preventive and corrective maintenance make the unit as good as new with the durations of inspections and maintenances being negligible. The existence of an optimum interval and how it depends on both the cost parameters and the reliability characteristics of the unit is discussed.

Aging properties of the additive and proportional hazard mixing models

Abstract We carried out a study of the aging characteristics in two mixing models having additive and proportional hazards, respectively. The relation between aging properties of such mixtures and that of an exponential mixture is described. The effect of mixing on the properties of the stochastic aging as well as the relation between the mixture and the distributions within are also analyzed.

Optimum Maintenance Policy of a Periodically Inspected System under Imperfect Repair

This paper deals with the maintenance policy of a system subject to periodical inspections aimed at detecting the occurrence of failures. After the first 𝑁−1 failure, the system undergoes an imperfect repair that brings the system back to the operating condition while the 𝑁th failure is followed by a perfect repair restoring the unit to an as-good-as-new condition. The limiting average availability as well as the minimum cost policy are discussed.

The DFR property for counting processes stopped at an independent random time

In the present paper we consider general counting processes stopped at a random time

ON THE BEHAVIOR OF AGING CHARACTERISTICS IN MIXED POPULATIONS

T

Stochastic comparison of multivariate conditionally dependent mixtures

, independent of the process. Provided that

Negative ageing properties for counting processes arising in virtual age models

T

Univariate and multivariate stochastic comparisons and ageing properties of the generalized Pólya process

has the decreasing failure rate (DFR) property, we give sufficient conditions on the arrival times so that the number of events occurring before

Optimal replacement policy under a general failure and repair model: Minimal versus worse than old repair

T

Stochastic comparisons and multivariate dependence for the epoch times of trend renewal processes

preserves the DFR property of